PROJECT SUMMARY One in three young adults engage in high intensity drinking (HID; 8+ drinks for women/10+ for men) in the past year, placing them at risk for serious acute consequences of alcohol use (e.g., severe injury, overdose). Further, one third to one half of young adult drinkers report alcohol-induced blackouts (AIB), an outcome distinct from HID episodes. Most research to date on HID and AIB has been cross-sectional, retrospective, and conducted exclusively in college students, revealing little about specific drinking events leading to HID or AIB. Needed also are objective indicators of the topography of drinking during these events, which is feasible with biosensor technology. Understanding more about drinking patterns, proximal antecedents and consequences of HID and AIB is imperative to the continued development and refinement of effective interventions for the most at-risk drinkers. The specific aims of this study are to: (1) elucidate the topography of drinking at the event-level during naturally occurring drinking events characterized by HID and/or AIB, using both self-reported drinking captured via ecological momentary assessment (EMA) and objective biosensor data; (2) determine event-level behavioral antecedents (pregaming, drinking games, protective behavioral strategies) and psychosocial antecedents (drinking motives, willingness, intentions, affect, social context), as well as positive and negative consequences of HID events; (3) isolate event-level factors that increase AIB risk beyond level of intoxication (co-use of other drugs, inadequate sleep, willingness, intentions); and (4) examine changes in frequency of and associations among HID, AIB, and related negative consequences across three annual assessments. First, key informant interviews (n=20-28) will be used to gather data on the relevance of theoretically-based cognitive and behavioral factors, social context, affect and other factors in the prediction of HID, as well as to identify consequences of HID for young adults. Next, in a measurement burst design, 200 young adults will complete in-person assessments and three 30-day bursts of daily EMA assessments at 12-month intervals, in combination with objective measurement of alcohol consumption using biosensor technology. We seek to differentiate the event-level predictors and outcomes of HID and AIB relative to all other drinking events, and relative to heavy episodic drinking (4+/5+ drinks), in order to isolate what places an individual at unique risk for these particularly concerning outcomes. Multilevel models will be used to determine predictors and outcomes as a function of whether each drinking event is characterized by HID or AIB. The results of the proposed research will provide novel information on proximal predictors of these two public health concerns among young adults. This innovative study will help to determine motivational targets for interventions, and in doing so, provide theoretical and empirical bases for designing preventive interventions to reduce HID, AIB and other severe alcohol-related consequences.